A novel mammalian cell (Vero) derived influenza virus vaccine: development, characterization and industrial scale production.

Influenza virus for vaccine production are presently produced in embryonated chicken eggs. This conventional standard methodology is extremely cumbersome; it requires a huge amount of eggs and an extensive purification to reduce the amount of contaminating egg proteins and to minimize the risk of allergies against egg albumin. The shortage of eggs in a pandemic situation, the selection of egg-adapted variants and the presence of adventitious viruses has emphasized the necessity for production of influenza vaccines on a well characterized stable cell line. Our established Vero cell technology has been successfully adapted to large scale production of a variety of influenza virus strains. The production in 1200 litre fermenter cultures under serum-free conditions gave antigen yields comparable to the conventional embryonated egg technology. The development of a rapid and efficient purification scheme resulted in a safe high purity vaccine which was at least as immunogenic as conventional egg-derived vaccines in a mouse model. This vaccine has been shown to be safe and highly immunogenic in chimpanzees and to be capable of protecting ferrets against challenge with live virus. Clinical trials have now been initiated in the UK and Austria.